The World Reference Center for Arvoviruses provides antigenic identification and biological characterization of viruses submitted to the the Yale Arbovirus Research Unit, designated by WHO as a Collaborating Centre. Between 100 and 200 viral strains are submitted for identification each year to the Center by field laboratories throughout the world. Directly related to this objective is the development of a systematic arrangement of the arboviruses within the higher classification of all viruses. This involves the placement of the arboviruses within recognized taxa based on morphology, morphogenesis, and physicochemical properties, and the establishment of new taxa when indicated. New techniques and methods are developed for the implementation of serological and physicochemical characterization of arboviruses. These will include polyacrylamide gel electrophoresis, monoclonal antibody, enzyme-linked immunosorbent assay, enzyme-linked fluorescent assay, and spot slide techniques among others. A bank of reagents to over 500 arboviruses is available at the Center which offers a unique diagnostic service for the recognition of etiological agents in epidemics and in clinically suspected arboviral infections of man or animals. This may involve virus isolation and identification, serological examination of paired sera or, occasionally, serosurveys. The final objectives are the training of personnel from laboratories throughout the world in arbovirus techniques; the distribution of reagents including seed virus, antigens, antibody, and tissue cultures to qualified laboratories; and the dissemination of information on arboviruses.